Novel superhard tetragonal BCN from crystal chemistry and first principles

Novel ternary equiatomic BCN compound structurally based on the 'glitter' C6 with both tetrahedral (sp3) and trigonal (sp2) carbons has been predicted using crystal chemistry rationale and supported by first principles calculations of energies and energy dependent quantities within density functional theory (DFT). Crystal structure of BCN belongs to the tetragonal space group P42mc and is built by stacking of corner sharing BC2N2 tetrahedra. The phase is found energetically cohesive and stable both mechanically (elastic properties) and dynamically (phonons band structures). The electronic band structures reveal metallic-like behavior. Characterized by very high Vickers hardness (65 GPa), BCN is expected to be a prospective superabrasive.